An ester of a tertiary alcohol having a non-aromatic ring group such as an alicyclic hydrocarbon group with a polymerizable unsaturated carboxylic acid is allowed to function as an acid-responsive compound because a part of alcohol is eliminated from the ester in the presence of an acid to become soluble in alkali. Therefore the ester focused in recent years is a compound as a monomer for a functional polymer such as a photosensitive resin, particularly a resist resin.
Generally, a tertiary alcohol ester can be synthesized by reacting an acid or an acid halide with a corresponding tertiary alcohol. A common acid-responsive tertiary alcohol ester, because of an acid-responsiveness thereof, is synthesized by reacting an acid halide with a corresponding tertiary alcohol under an amine such as triethyl amine.
However, it has been hard to efficiently produce a tertiary alcohol ester having a tertiary carbon atom bonding with a non-aromatic ring such as a bulky alicyclic hydrocarbon ring by the above-mentioned technique from the corresponding tertiary alcohol. More concretely, when reacting an acryl halide with a tertiary alcohol, which has a tertiary carbon atom bonding with a bulky non-aromatic ring, under an amine such as triethylamine, it has been difficult to efficiently obtain a corresponding acrylic acid ester because there have been problems; many polymeric compounds of a corresponding acrylic acid ester are generated, a concentration of substrate can't be increased because of much deposition of a salt and so on. Furthermore, in case of reacting a methacrylic acid halide with the alcohol having a tertiary carbon atom bonding with a bulky non-aromatic ring under an amine such as triethylamine, a desired methacrylic acid ester is hardly produced due to the low reactivity thereof.
Thus an efficient esterification of the tertiary alcohol having a branched chain thereof bonding with a non-aromatic ring such as a bulky alicyclic hydrocarbon ring is hardly carried out due to the following reasons; a low reactivity according to a bulkiness thereof and an easy elimination of an ester portion caused by having an acid-responsiveness. Such problem can be also caused when a carboxylic acid portion is not only an unsaturated carboxylic acid but also a saturated aliphatic carboxylic acid, an aromatic carboxylic acid and so on. Further, the above problem can be caused in case of not only the tertiary alcohol having a branched chain bonding with a non-aromatic ring but also a tertiary alcohol bonding with an aromatic ring.
Furthermore, to add to the above problems in the esterification, an alcohol compound used as a raw material is desired to produce separately and therefore the following problems are also caused; a complication of operation and a time demerit in a production.